The Catalytic Performance of Ultrasonically Prepared AlPO4 Nanocatalysts for the Selective Production of Dimethyl Ether from Methanol

Conversion of methanol to dimethyl ether (MTD) has known to be one of the main routes for the production of a clean bio-fuel, i.e., dimethyl ether (DME). However, efficient, selective, and stable catalyst is highly required for production of DME especially at relatively low temperature. Herein, aluminum phosphate nanocatalysts were fabricated by a co-precipitation method in the presence of triethylamine (TEA) as a surfactant. Thermal, structural, spectroscopic, morphological and texture properties of the catalysts were characterized by thermal analyses (TG-DTA), X-Ray diffraction (XRD), Fourier transform infrared (FTIR), high resolution transmission electron microscopy (HR-TEM) and N-2-sorption analyses. In addition, the acidity of these catalysts was evaluated by isopropyl alcohol dehydration and chemisorption of basic probes. Results of acidity and pyridine-TPD indicated that these catalysts possessed Br phi nsted acidic sites of weak and intermediate strengths. The results of catalytic activity demonstrated that aluminum phosphate nanocatalyst (AP(1)T(1)) calcined at 400 degrees C exhibited the best catalytic performance for methanol dehydration into DME with a conversion of 100% and a 100% selectivity at 250 degrees C. In addition, this catalyst (AP(1)T(1)) exhibits a unique behavior where its catalytic performance only decreases by 10% upon increasing the % of methanol in the reacting feed to 35%. Moreover, it possessed excellent long-term stability with almost the same efficiency after a period of 120 h. The observable catalytic activity of these catalysts was well linked to the catalyst acidity and the activation energy.